Summary Of Significant Accounting Policies (Schedule Of Other Accruals And Current Liabilities) (Details) - USD ($) $ in Thousands	Mar. 31, 2016	Sep. 30, 2015
Summary Of Significant Accounting Policies [Line Items]
Regulatory Liabilities	$ 20,786	$ 5,346
Reserve for Gas Replacement	(8,599)	(34,252)
Other	24,045	30,703
Other Accruals and Current Liabilities	104,925	96,557
Accrued Capital Expenditures [Member]
Summary Of Significant Accounting Policies [Line Items]
Other	38,299	53,652
Reserve For Gas Replacement [Member]
Summary Of Significant Accounting Policies [Line Items]
Reserve for Gas Replacement	17,469	0
Federal [Member]
Summary Of Significant Accounting Policies [Line Items]
Income Taxes Payable	4,102	5,686
State [Member]
Summary Of Significant Accounting Policies [Line Items]
Income Taxes Payable	$ 224	$ 1,170